Grey water reuse in buildings: The Portuguese approach

The Mediterranean climate, which influences a large part of the Portuguese territory, creates specific problems in the management of water resources, whose worsening, in terms of the water balance, is forecast in the short/medium term.

In fact, various entities, such as the United Nations Environment Programme or the World Water Council, warn that, within a few decades, the Mediterranean basin will be one of the regions on the planet with the greatest water stress or water scarcity problems.

The annual use of water in Portugal is, in average terms, 10km3, still less than that available in an average year (16km3), but the typical seasonality of the Mediterranean climate and the irregularity of the spatial distribution of this resource (in addition to the effects of climate change) mean that, in some regions of the country, there are growing situations of shortage. Affected by some serious droughts in recent decades, Portugal has paid growing attention to this matter even though government policies in this area for the efficient use of water are not very inconsistent and are relatively weak.

The problems are made worse by the high losses and inefficiencies in water management. Portugal has the 6th largest water footprint in the world, with an indicator of 2.26 million litres per inhabitant per year. In a study prepared by the Portuguese Government in 2001, designated by PNUEA – National Programme for the Efficient Use of Water, the losses and inefficiencies in the various sectors of water users were estimated at about 3,100 m3/year, corresponding to almost 40% of total demand for water in the country.

With the objective of increasing the efficiency of water use, the PNUEA has established various areas of intervention, including, in the urban sector, 50 specific measures to be implemented with the involvement of government entities, sector entities, water authorities, consumers and non-governmental organisations.

Even though the PNUEA did not have the implementation planned by the Portuguese Government, it brought awareness to society of the extent of the water management problem in Portugal and the need to study and apply water efficiency measures on all levels, including the building sector. As a consequence, some universities, companies and municipal water authorities decided, in 2007, to create a non-profit NGO called National Association for Quality in Building Installations (ANQIP), aimed at the promotion of water efficiency in buildings, among other objectives.

Taking into consideration the measures proposed in the PNUEA for the building sector, ANQIP sought to systematise the interventions leading to an efficient use of water in the building cycle, establishing a guiding principle called “the 5R principle”, which is summarised in Figure 1.

Figure 1 – The 5Rs principles for water efficiency in buildings (ANQIP)

Regarding the systems of re-use and recycling of grey water in buildings, the lack of standards and regulations in Portugal led to some experiences which revealed risks to public health due to deficiencies in design, operation or maintenance.

In this respect, ANQIP believed that, in these systems, special attention should be given to water safety aspects. In fact, this understanding within the Bonn Charter recommendations, published by the International Water Association for the supply of water, argues that the management and control of systems should be based on a Safety Plan, in accordance with WHO guidelines, considering resources, technology available and the reality of each country.

To establish technical recommendations and guidelines for projects, ANQIP has drawn up the Technical Specification ETA 0905 (which can be found in www.anqip.com ), which states that a Security Plan must also be prepared for reuse systems and gray water recycling in buildings, with an initial version of the responsibility of the installer, but which is periodically updated by the user.

For public health and technical reasons, the systems must also be certified under the terms of Technical Specification ANQIP ETA 0906, which requires a prior analysis of the project by ANQIP, inspections during construction, the certification of installers, a maintenance plan and the Safety plan, also approved by ANQIP.